Mercedes-AMG has a new hypercar in the works, tentatively dubbed Project One, which borrows their F1 car’s tech.

But as seldom as Daimler has been known to compete at this level, the forthcoming game-changer won’t be the first. In fact there’s a rather spectacular piece of Silver Star exotica coming up for auction, and we want it. Badly.

It’s a 1998 Mercedes-Benz AMG CLK GTR – a rare homologation special that was produced in exceedingly limited quantities. This was the ninth of only 25 made, it’s already registered for (occasional) use on American roads, and it has less than 1,500 kilometers (932 miles) on the clock.

The GTR was the road-going version of the racer that dominated the FIA GT Championship from its infancy for two years running. And it had an even bigger engine: where the racer employed a 6.0-liter V12, the road model’s was bored out to 6.9, sending 604 horsepower (450 kW) and 572 lb-ft (775 Nm) of torque to the rear wheels through a six-speed sequential gearbox. With an F1-style inboard suspension and a curb weight of just 3,175 pounds (1,440 kg), it could hustle to 62 mph (100 km/h) in just 3.8 seconds and reach a top speed of 214 mph (344 km/h).

Mercedes built no more road-going examples than it had to in order to meet homologation requirements: just 20 coupes and another five roadsters. And it sold each for over $1.5 million, making it the most expensive “production” car up to that point in history, long before Bugattis and Paganis were pushing prices ever higher.

Chassis number 9 was one of the few that were imported into the United States, prepared by J.K. Technologies and registered under Show or Display regulations. So while you might not get away with driving it every day, it can be used on public roads from time to time. Which is probably just as well, considering that this is about as close as a race car for the road as you’re ever going to find, and despite its luxury badge, has little in the way of creature comforts.

Given its extreme rarity, RM Sotheby’s expects it will sell for a good $4.25-5.25 million when it crosses the auction block in Monterey less than a month from now on August 25. If that seems like a big chunk of change to you… well, it is. But it probably won’t even be the top lot at the sale, which already has more than 35 lots consigned that are valued in excess of a million dollars – including a rare Aston Martin (valued at around $20 million), and a Ferrari 250 GTO that could prove the most expensive car ever sold at auction, as it has an estimate of $45-60 million.